Circuit breakers provide protection in electrical systems by monitoring characteristics of the electrical power supplied to loads over electrical conductors and interrupting or breaking the circuits (tripping) when fault conditions (e.g., arc faults, ground faults, and unsafe “over current” levels) are detected. Circuit breakers are typically installed in circuit breaker panels, or load centers, often in utility rooms for commercial applications and basements for residential applications.
Many existing circuit breaker panel installations provide only limited information to electricians and consumers about the nature of the fault conditions observed by the circuit breakers. For example, a residential consumer may only be able to determine that a circuit breaker has tripped, without knowing why. More sophisticated circuit breakers include circuitry for detecting arc faults and ground faults. Ground faults may occur when the electric current is not balanced between an energized line conductor and a neutral conductor, for example when the current is being grounded through a person accidentally touching the circuit. Arc faults occur with dangerous arcing due to defective or damaged wiring, switches, etc. Circuit breakers designed to detect ground faults and arc faults may include circuitry for monitoring the line current of the branch to which the circuit breaker is connected and a controller for processing the data sensed from the line current. The controller may also include memory for storing such data. However, this data is typically only used by the circuit breaker in making a decision to trip. Once again, a consumer or electrician can determine that a circuit breaker has tripped, but has no visibility into the conditions that caused the trip.
This data, if it were accessible outside the circuit breaker, could be valuable for monitoring the individual branch over time, and also in conjunction with similar data from other circuit breakers in the system useful for monitoring the system as a whole. For example, electrical usage on individual branches could be tracked, faulty wiring could be identified prior to a circuit tripping, etc. As smart grid technology becomes more prevalent, it is becoming more desirable to extract as much information as possible from circuit breakers.
However, it is difficult and expensive to retrofit an existing electrical system with circuitry capable of monitoring and aggregating the data from a plurality of circuit breakers. For example, it may be necessary to modify existing circuit breakers with additional circuitry and external wired connections to gather and make branch circuit state information available and accessible. Circuit breaker panels would then need to be retrofitted with additional circuitry to interface with the additional wired connections of the modified circuit breakers. The additional labor necessary to install the additional circuitry, which would typically be performed by an electrician or engineer, can be involved and expensive. In such cases, it may be more cost effective to add an entirely new circuit breaker panel with new circuit breakers instead of retrofitting existing equipment.
Moreover, space in circuit breaker panels is often at a premium. As consumer demand for electronics increases, existing electric systems must accommodate greater electrical usage. Miniature Circuit Breakers (“MCB”) have been introduced to maximize the space in circuit breaker panels. MCBs are now commonly used for residential circuit breakers and include a substantial installed base. Adding functionality to MCBs is desirable because of the opportunity to take advantage of the large installed base. However, retrofitting MCBs is made more complicated because these packages are already space-constrained. Because of the limited space in the panel, it is often not practical to retrofit an existing circuit breaker by augmenting it with components and wiring outside of the circuit breaker housing and within the panel. For example, there may be insufficient room in the branch circuit wiring space of a panel to accommodate components such as current transformers and associated wiring. This is made more challenging and expensive because components outside of a circuit breaker package are exposed to damage and must be protected with some form of housing, which adds to materials cost and the space the additional components consume. Thus, designers are faced with a dilemma in which space constraints in the circuit breaker panel make it disadvantageous to increase the size of or augment existing circuit breakers, yet the small size of circuit breakers makes it difficult to increase their functionality within the existing packages of circuit breakers themselves.